| 摘要 |
PROBLEM TO BE SOLVED: To allow the circuit to accurately detect a phase deviation in differential phase shift keying(DPSK) modulation. SOLUTION: A monitor circuit 7 compares an output voltage of a mixer 4, in the case of DPSK modulation in a 0-status with a mixer output voltage in the case ofπ-status, to detect a phase deviation in the case ofπ-status. On the other hand, offset detection circuit 8 monitors an output voltage of the mixer 4, when DPSK modulation denotes 0-status to detect an offset, so as to change a phase shift of a programmable phase shifter 9 depending on the detected offset. Thus, the phase deviation in the DPSK modulation is detected accurately for all operating frequencies.
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